The present invention relates to microelectronic packaging and more particularly relates to methods of making connectors and packaged microelectronic components. In various microelectronic devices, it is desirable to provide a connection between two components, which can accommodate relative movement between the components. For example, where a semiconductor chip is mounted to a circuit board, thermal expansion and contraction of the chip and circuit board can cause the contacts on the chip to move relative to the corresponding electrically conductive features of the circuit board. This can occur during service and can also occur during manufacturing operations as, for example, during soldering operations on the circuit board.
As illustrated in certain preferred embodiments of U.S. Pat. No. 5,518,964 (xe2x80x9cthe ""964 patentxe2x80x9d) movable interconnections between elements such as a semiconductor chip and another element can be provided by first connecting leads between the elements and then moving the elements away from one another through a preselected displacement so as to bend the leads. For example, a connection component may incorporate a dielectric body and leads extending along a bottom surface of the dielectric body. The leads may have first or fixed ends permanently attached to the dielectric element and connected to electrically conductive features such as terminals, traces or the like on the dielectric body. The leads may also have second ends releasably attached to the dielectric body. The dielectric body, with the leads thereon, may be juxtaposed with the chip and the second ends of the leads may be bonded to contacts on the chip. Following bonding, the dielectric body and chip are moved away from one another, thereby bending the leads towards a vertically extensive disposition. During or after movement, a curable material such as a liquid composition is introduced between the elements. This is cured to form a compliant dielectric layer such as an elastomer or gel surrounding the leads. The resulting packaged semiconductor chip has terminals on the dielectric body connection component which are electrically connected to the contacts on the chip but which can move relative to the chip so as to compensate for thermal effects. For example, the packaged chip may be mounted to a circuit board by solder-bonding the terminals to conductive features on the circuit board. Relative movement between the circuit board and the chip due to thermal effects is taken up in the moveable interconnection provided by the leads and the compliant layer.
Numerous variations of these processes and structures are disclosed in the ""964 patent. For example, the package-forming process can be conducted on a wafer scale, so that the numerous semiconductor chips in a unitary wafer are connected to connection components in one sequence of operations. The resulting packaged wafer is then severed so as to provide individual units, each including one or more of the chips and portions of the dielectric body associated therewith. Also, the leads may be formed on the chip or wafer rather than on the dielectric body. In further embodiments, also disclosed in the ""964 patent, a connector for use in making connections between two other microelectronic elements is fabricated by a generally similar process. For example, in one embodiment a dielectric body having terminals and leads as discussed above is connected to terminal structures on a temporary sheet. The temporary sheet and dielectric body are moved away from one another so as to bend the leads, and a liquid material is introduced around the leads and cured so as to form a compliant layer between the temporary sheet and the dielectric body. The temporary sheet is then removed, leaving the tip ends of the terminal structures projecting from a surface of the compliant layer. Such a component may be used, for example, by engaging it between two other components. For example, the terminal structures may be engaged with a semiconductor chip, whereas the terminals on the dielectric body may be engaged with a circuit panel or other microelectronic component.
Thus, the broad invention taught in the ""964 patent offers numerous desirable ways of making electrical interconnections and connectors.
In a first aspect of the present invention, an interconnect component comprises a compliant layer and a plurality of electrically conductive leads having first ends and extending through the compliant layer. The first ends comprise elongated portions of the leads exposed at a first surface of the compliant layer and are located at or near said first surface.
In certain preferred embodiments, the compliant layer has a second surface opposite the first surface. The leads desirably have second ends opposite the first ends and the second ends are located at or near the second surface of the compliant layer.
The leads may have any shape. In certain preferred embodiments, the leads have midsections with a width less than the width of the first ends. The leads may have midsections with a width less than the width of the second ends.
The first ends of the leads may be located at upper sides of said leads and the second ends may be located at lower sides of the leads so that the upper sides are exposed at the first surface of the compliant layer and the lower sides are exposed at the second surface of the compliant layer.
In certain embodiments, releasable bonding material is disposed on the first ends. The releasable bonding material may comprise any releasable bonding material. The releasable bonding material may comprise an adhesive or a solder. Releasable bonding material may be included on the second ends of the leads.
In certain embodiments, the component comprises a temporary support structure. The first ends are connected to the temporary support structure. The component may include a first temporary support structure and a second temporary support structure. The first ends are desirably connected to the first temporary support structure and the second ends are desirably connected to the second temporary support structure. In certain embodiments, the leads extend between the first temporary support structure and the second temporary support structure in a generally vertical configuration.
In a further aspect of the present invention an interconnect component comprises a compliant layer having a first surface and a plurality of electrically conductive leads having first ends and extending through the compliant layer. The first ends extend generally parallel to the first surface.
In certain preferred embodiments, the compliant layer has a second surface opposite the first surface. The leads desirably have second ends opposite the first ends. The first ends are located at or near the first surface and the second ends are located at or near the second surface of the compliant layer.
The leads may have any shape. In certain preferred embodiments, the leads have midsections with a width less than the width of the first ends. The leads may have midsections with a width less than the width of the second ends.
The first ends of the leads may be located at upper sides of said leads and the second ends may be located at lower sides of the leads so that the upper sides are exposed at the first surface of the compliant layer and the lower sides are exposed at the second surface of the compliant layer.
In certain embodiments, releasable bonding material is disposed on the first ends. The releasable bonding material may comprise any releasable bonding material. The releasable bonding material may comprise an adhesive or a solder. Releasable bonding material may be included on the second ends of the leads.
In certain embodiments, the component comprises a temporary support structure. The first ends are connected to the temporary support structure. The component may include a first temporary support structure and a second temporary support structure. The first ends are desirably connected to the first temporary support structure and the second ends are desirably connected to the second temporary support structure. In certain embodiments, the leads extend between the first temporary support structure and the second temporary support structure in a generally vertical configuration.